I am deeply sorry for your loss of Jack, your precious kitty. I understand how devastated you feel ... you and Jack had a very deep loving bond, he was your special guy.
Your pain is very raw right now. Your loss is so recent. Most of us her at the forum have been through similar losses and have asked ourselves very similar questions, like yours of how do I get through the days, the pain, the loss. We all have to grieve for our beloved pets. Slowly we go forward. But we do. It is difficult. But we do.
I would urge you to use this forum regularly to help yourself in this process. There are many wonderful people here who care about what you going through right now and want to listen to you and want to comfort and help you best they can. In this way you are not alone.
Jack will forever be in your heart and your memories.